[Archived]

I looked through the various Prevost publications and that is one dimension I could not find. How accurate does the dimension have to be?

[needtocamp]

Just within a couple inches. Just wanted to see for the sake of making ramps and their being plenty of tire on the top of the stack (for the wood) to make sure Im not going to back off trying to get both the drive and tag axle on safely.

[Dick]

In that case you might want to approach the dimensions from a different direction.

The tire diameter is approximately 42″, and for this discussion assume 8″ between wheels so the dimension you seek is 50″.

But I don’t think you want to have a flat platform top on the ramps the length of the center to center dimension because it means 1/2 of one tire is hanging over the front of the ramp when the 1/2 of the other tires is just at the top of the sloped portion. That would work in a perfect world but for placement it would be almost impossible to position the bus that way safely.

I know every extra inch either adds weight, or might affect the steepness of the ramps but to get the bus up onto the flat with some degree of safety I would be more comfortable with as much flat at the top of the ramps as you can afford to provide. I do not think it would be beyond reason to go 18″ greater than the center to center or even more. If you think about it the greater the flat portion the steeper the slope, or conversely the shorter the flat the more shallow the slope meaning each way you bias your dimensions creates its own potential issues.

I can assure you if you add a stop at the end of the flat portion it has to be pretty high because even with my bus idling uphill it goes over the 1 1/2″ lip into my garage with no hesitation so my preference would lean toward maximizing the flat portion.

[Harry]

At the risk of sounding naive or uninformed …

Aren’t the center to center distances between the drive axle and the tag axle pretty much the same on all the Prevost coaches? From XL to XLV to XII to X3?

A good number of the members have made ramps. I think it would be very helpful if a number of them would post pictures and the measurements of their respective ramps. I’m wondering if any of the ramp builders built their ramps solid across, or put spacers in between every one or two boards to keep the total weight lighter. Anyone drill holes in the boards to lighten? What is height of the ramps … 4″ or 6″ 8″ or more?. What is the length of the incline? What is the height of the landing pad? Everyone using Douglas fir?

I concur with what Jon said about not being able to “feel” a “stop block” with the coach because of the weight. i learned this very quickly with the Suburban and 10,000# to 11,000# trailer. About the only thing you can “feel” is when you’re solidly up against something!

Most of us who’d like to build ramps aren’t too interested in reinventing the wheel and going through two or three or even maybe four different iterations to get ramps that work.

[Dan]

I’m with Dick, I would like to build a set but not reinvent the whole process. I know that Fred just bought a set and maybe he would post some pictures and measurements and say what he likes and dislikes about his.

[needtocamp]

Here’s what I did, had the lumber center rip 8 sheets of 4×8 3/4″ plywood down the center. Cut them down 4.5″s at a time, and wood screwed them together. Total step is 31.5″s, 6″ height, 64.5″ platform length. For the front I went with 12″ width. I’m adding a 4X4 block on the ends and hinging them so I can easily stack them. $380 total

I believe Gerald used 6 one inch thick sheets, IIRC

[Andre]

I will be back home this evening and will take measurements and photos of my set. They are 2X8 on edge with open spaces between to lessen weight. They are bolted together using all thread. Will add demensions and photos upon return.

3-F

[Archived]

Thanks for the measurement Jon.

I have thought about cutting strips of 4X8 sheets of plywood. Good to know that is a route to take.

Somebody stop me if Im headed in the wrong direction but I was going to go with 2X12 boards. Figuring the actual measurment is 1.5″ and cutting the board at an angle it should work. The top board for the drive/tag axles to go on would be 60″ long. With the rise at 1.5″ and the run measuring 8″, the bottom board will be 108″ long, these suckers are going to be heavy but I will not have to move them far at all. This will give me an angle stepping up about 10 inches over a distance of about 4ft.

The front ramp will be the same but have a top board measuring 24″.

Is 10″ too high to go up? The coach at ride height should be 11″ letting the ramps still slide right under the chassis. I might overcharge the airbags using the low level system to drive up them. Any pitfalls there?

It is much easier and cheaper to discuss this with PC than to build something that will turn into firewood.

[AL]

If you have to rely on raising the coach over drive height you just have to be certain of two things.

First no matter what the ultimate chassis height ends up with the bus on the ramps, you still have to support the chassis when you are under it unless you plan on lowering it all the way down when it is on the ramps. With ramps the rear support points on the chassis might be over the ramp so you might have to make the ramp wider to carry the support, or narrower to clear the support. Look at your plans relative to the support of the chassis.

The second concern is finding the ideal height. With the coach sitting on the floor, but the chassis at the highest point you have a lot of freedom of movement once you get into the area between the wheels, front or back. You will be sitting on the floor but still able to do a lot of the jobs that are going to take place on the bus. As you get higher your reach may not allow you to easily get at some things like the relay valves or the Norgren valves located on the upper frame. If you have the air dryer mounted on the passenger side of the frame ahead of the drive axle it will be almost impossible to replace the cartridge because of its height you cannot get the torque you need without spinning your ass across the garage floor. I worked for 10 years off my garage floor and the biggest advantage of the pit is I can brace myself when working on something that takes a lot of force to repair, whereas on the floor I had nothing to brace my legs or feet against so I did some sliding on some jobs. Guys with ramps will have to tell you the ideal height. I don’t think high ramps as you describe would be best, but that is just a guess.

[Archived]

Jon,

Excellent point on making sure the support points are still available to receive the jack stands as well as having clearance from the ramps.

Ill admit I never thought about what would be the most effective height. I initially though the higher the better. Im 6’2″ and can pretty much access anything I can reach but wanted to be able to fit everywhere safely.

I will do some more measuring and see what would work best for my application.

Thank you everyone for the help.

[Harry]

I never realized until I had my pit how much my butt spun on the garage floor from trying to use a lot of upper body strength to loosen stubborn fittings, fasteners or parts. That means the further from you body parts are the more you will slide loosening them. For almost 100% routine work like lubing the chassis, draining air tanks, oil and filter changes, checking fluid levels, and even parts replacement like air bags or some low mounted valves any reasonable height is going to work.

[Archived]

I had some time this weekend and got all the measurements. About 9 inches is all the higher I would want to make the ramps to safely slide under the coach before I back the coach on at ride height. I thought this would be good height for all the ramps BUT as usual, it will not work on the back driver side b/c the ramp wont slide under due to the Webasto and generator exhaust pipe/tips. The U-bolts holding the tips on hang down about 5-6″ from the ground. If I can only get 5 inches, I might as well not even have ramps from what it looks like.

I dont see any other way but to overcharge the airbags to back the coach on the ramps, or at least over charge the rear bags making sure I dont damage the exhaust pipes. I dont think I have a problem doing that but ride height would be ideal in my mind.

Also, about 11″ of tire touches the ground on a 315/80R22.5. With that, Im going to make that top board 30″ in the front and 72″ in the rear to at least look safe enough to drive on.

[Archived]

If your ramps are 9″ high they should slide under the coach in front of the drive axle so instead of backing on them you can drive on them. Normal ride height puts most everything except the generator baffle about 11″ off the ground.